The present invention relates to the field of multi-spool gas turbine engines used in aeronautics. It is aimed at the way in which auxiliary electrical machines are driven by the shafts of the engine.
In turbine engines used for the propulsion of aircraft, some of the power produced is tapped off to drive auxiliary equipment providing ancillary services both to the engines themselves and to the aircraft. This equipment includes the lubricating and fuel systems, and the power supply for the hydraulic and electrical systems.
A multi-spool gas turbine engine comprises at least two rotary spools; most have two or three spools, but a higher number is not excluded. A spool consists of a unitary assembly rotating about an axis, with one section forming a compressor and one section forming a turbine, the latter driving the compressor. More specifically, a multi-spool engine may also be a multi-flow engine, generally a dual flow or bypass engine, and comprise a fan generating a cold secondary or bypass flow that bypasses the central core containing combustion chamber and through which the hot primary flow passes. The engine may also be of the turboprop type, driving a propeller.
In general, all of the mechanical power needed to drive the auxiliary machines is tapped off the high pressure HP spool via a gearbox known as the IGB which stands for inlet gearbox, and is then transmitted to the equipment situated on the fan casing by a shaft arranged radially with respect to the engine drive shaft, in mesh with a gear set forming the box supporting them and known as the AGB which stands for auxiliary gearbox.